The present invention generally relates to a method for the production of a superabsorbent composition, a superabsorbent composition obtainable by said method, a particulate superabsorbent composition plus a composite, a sanitary article core and a sanitary article and furthermore chemical products, such as foams, shaped bodies, fibers, sheets, films, cables, sealing materials, liquid-absorbing sanitary articles, carriers for means to regulate plant and fungal growth, packaging materials, soil additives or building materials, each containing an absorbent composition and also the use of this superabsorbent composition in the chemical products.
Superabsorbers are water-insoluble, crosslinked polymers which are capable of absorbing large amounts of aqueous liquids, in particular body fluids, such as urine or blood, with swelling and the formation of hydrogels and of retaining them under pressure. Generally, this liquid absorption amounts to at least 10 times or even at least 100 times the dry weight of the superabsorber or the superabsorbent composition in water. As a result of these characteristic properties, these polymers are predominantly used in sanitary articles, such as babies' diapers, incontinence products or sanitary towels. A comprehensive overview of superabsorbers or superabsorbent compositions, their application, and their production is provided by F L Buchholz and A T Graham (editors) in “Modern Superabsorbent Polymer Technology”, Wiley-VCH, New York, 1988.
Superabsorbers may be produced by means of the radical polymerization of acid-group-bearing, partially neutralized monomers in the presence of crosslinking agents. Here, the choice of the monomer composition, the crosslinking agents, the polymerization conditions and the processing conditions for the hydrogel obtained following the polymerization allows the production of polymers with different absorber properties.
Absorbent polymers substantially based on saccharides such as cellulose and starch have been known and are the subject of research today with the objective of improving suitability for use in diapers; these are described inter alia in WO 2004/085481 A1. In order to improve their absorption and retention properties, polysaccharides of this type are copolymerized with acrylic acid. Although this copolymerization did improve the absorption and retention properties of copolymers of this kind, the biodegradability of copolymers of this kind suffered with the use of this measure. In recent times, the trend has been increasingly toward the almost exclusive production of superabsorbers based on acrylic acid or acrylates since these loosely crosslinked, partially neutralized polyacrylates have the best absorption, retention and permeability properties compared to polysaccharides or polysaccharide-acrylate copolymers and, in particular in the form of surface or post-crosslinked superabsorbent polymers, are particularly suitable for the production of absorbent layers with a high filling of superabsorbers (generally with more than 50% of superabsorbers) which in turn are excellent for processing into sanitary articles, in particular female sanitary articles, babies' diapers and incontinence products, in order to obtain sanitary articles with excellent wearing and functional properties.
Unfortunately, these superabsorbent polymers, which are virtually exclusively based on acrylic acid or acrylates, have an inadequate level of biodegradability. In the light of the increasing environmental awareness of consumers requiring sanitary articles, environmental requirements for sanitary articles have increased considerably over recent years. However, more environmentally friendly sanitary articles may only be successfully marketed if their other functional properties are not noticeably worse than those of conventionally produced, and hence less environmentally friendly, sanitary articles.
An object of the present invention is to reduce or even overcome the drawbacks resulting from the prior art.